so you can build a directory with each category "full" with links whats the use for a directory with no links in it?
that is why you dont approve every site you go to the site and check if its suitable to be listed in your directory even with featured links or paid inclusions you should still approve/dissaprove them by checking the quality of the site and refund them
If you have a paid section or paid feature link, you will need that to get more listing. no one is going to paid for inclusion at a directory with no much listing, just my 2c